The present invention relates generally to transmission shifting systems and more particularly to electronic shifter assemblies.
Modern automotive vehicles having automatic transmissions typically employ a driver-operated mechanical shifter assembly which controls the transmission. Such shifters generally employ a shift lever which may be moved by hand between several gear settings, the lever typically being mounted for rotation about a pivot point. While such systems are widely used, several drawbacks have been noted.
To eliminate these drawbacks associated with mechanical shifter assemblies, it is proposed that an electronic shifter assembly be used to shift the transmission into a desired gear setting. The electronic shifter does not use the traditional mechanical transmission cable to physically shift gears but rather transmits an electric signal to an electronic control box that actuates the shifting. This type of electronic shifting system is often referred to as xe2x80x9cshift-by-wire.xe2x80x9d
A drawback with conventional electronic shift systems is the potential loss of transmission control when there is a power, electrical, or system failure. That is, the operator could lose the ability to shift gears. This could cause the inability to even shift the automobile into neutral in order to enable the automobile to be towed.
It is an object of the present invention, to provide a shift-by-wire shifter assembly with mechanical override.
In accordance with a first aspect, a shift-by-wire shifter assembly comprises a shift lever, a sensor, a cable bracket, and a lever lock. The lever is movable between shift position locations. The sensor is operative to detect the shift position location of the lever and generate an electrical signal corresponding to the shift position location of the shift lever. The cable bracket has a transmission shift cable mount, typically operative to receive the end fitting of a transmission shift cable or the like. The lever lock is operative in a first condition to releasably interlock the shift lever to the cable bracket for movement of the cable bracket with the shift lever between shift position locations, and has a second condition in which the shift lever is movable between shift position locations independently of the cable bracket.
In accordance with a second aspect, a shift-by-wire shifter assembly comprises a housing, a shift lever, a sensor, a cable bracket, and a sleeve. The shift lever is pivotally mounted to the housing and moveable between shift position locations. Typically, the lever extends from an upper portion of the housing and is operative to move through a series of shift positions locations corresponding to transmission settings. The sensor is attached to the housing and operative to detect the shift position location of the shift lever and to generate an electrical signal corresponding to the shift position location of the shift lever. The cable bracket is pivotally mounted to the housing and is configured to receive the shift lever. In a first condition the cable bracket moves with the shift lever through the various shift position locations and mechanically controls the transmission via the transmission shift cable. In a second condition the cable bracket does not move with the shift lever and it is the signal generated by the sensor that controls the transmission. The sleeve is slidable along at least a portion of the length of the shift lever and configured to engage the shift lever to the cable bracket for movement of the cable bracket with the shift lever between shift position locations. In a typical embodiment the sleeve is slid toward the end of the shift lever pivotally mounted in the housing to engage the shift lever with the cable bracket in the first condition wherein the cable bracket moves with the shift lever. The sleeve is slid away from the pivot mount of the lever to place the cable bracket in the second condition wherein the cable bracket does not move with the shift lever.
In accordance with another aspect, a shift-by-wire shifter assembly comprises a base, a yoke sub-assembly, a shift lever, a sensor, a cable bracket, a lever lock, components of a brake transmission interlock (BSTI) system, and a shifter knob. The yoke subassembly comprises detents corresponding to shift position locations and a pivot pin for pivotally mounting the yoke sub-assembly to the base. The shift lever is attached to the yoke sub-assembly. The sensor is attached to the base and operative to detect the shift position location of the shift lever and to generate an electrical signal corresponding to the shift position location of the shift lever. The cable bracket is pivotally mounted on the pivot pin of the yoke sub-assembly and has a transmission shift cable mount, typically operative to receive a transmission shift cable. The lever lock comprises a sleeve slidable along at least a portion of the length of the shift lever and is operative in a first condition to releasably interlock the shift lever to the cable bracket for movement of the cable bracket with the shift lever between shift position locations, and has a second condition in which the shift lever is movable between shift position locations independently of the cable bracket. The components of a brake transmission interlock system include at least a BTSI lever pivotally mounted on the pivot pin of the yoke sub-assembly and a solenoid in communication with the BTSI lever. The shifter knob is mounted on a free end of the shift lever opposite of the yoke sub-assembly and operative to operate the lever lock.